This invention relates to a magnetic recording disc, and more particularly to a magnetic recording disc in which a magnetic sheet for recording and reproducing electric signals is easily held on a rotating disc and is stably in contact with a magnetic head.
Recently, a disc has been widely used as a magnetic recording medium for a memory device for digital information, video signals or the like. Conventional discs for magnetic recording are very expensive because it is necessary that the surface of the magnetic recording disc be finished and kept perfectly flat in order to get good recording results. Moreover, maintenance of the magnetic recording disc is very troublesome, and it is difficult to replace the recording disc by a new one while maintaining the flatness of the surface of the disc.
Therefore, it has been desired to develop a magnetic recording disc in which the magnetic recording medium can be kept perfectly flat, which has a simple construction and is easy to maintain. Particularly, when a magnetic recording disc is used for recording and reproducing electric signals at different rotating speeds of the disc, it is necessary that there be no difference in the magnetic head pressure with respect to the magnetic sheet.
Recently, we proposed a novel and improved magnetic recording disc in a prior patent application entitled "Magnetic Recording Disc," Ser. No. 273,967, which was filed on July 21, 1972, now U.S. Pat. No. 3,805,292 for fulfilling such requirements. The present invention relates to a further improvement of the magnetic recording disc of the above mentioned application.